Moving picture coding method, moving picture coding apparatus, moving picture decoding method, moving picture decoding apparatus and moving picture coding and decoding apparatus

ABSTRACT

By the moving picture coding method and the moving picture decoding method, it is possible to improve coding efficiency. The moving picture coding apparatus includes a merge block candidate calculation unit that (i) specifies merge block candidates at merge mode, by using colpic information such as motion vectors and reference picture index values of neighbor blocks of a current block to be coded and a motion vector and the like of a collocated block of the current block which are stored in a colPic memory, and (ii) generates a combined merge block by using the merge block candidates.

TECHNICAL FIELD

The present invention relates to moving picture coding methods of codinginput image on a block-by-block basis using inter-picture predictionwith reference to coded picture(s), and moving picture decoding methodsof decoding a bitstream on a block-by-block basis using inter-pictureprediction.

BACKGROUND ART

In moving picture coding, generally, an information amount is compressedby using a redundancy of a spatial direction and a temporal direction ofmoving pictures. Here, in general, one of the methods using a redundancyin a spatial direction is transformation to a frequency domain, and oneof the methods using a redundancy in a temporal direction isinter-picture prediction (hereinafter, referred to as “interprediction”) coding. In the inter prediction coding, when a currentpicture is to be coded, a coded picture prior or subsequent to thecurrent picture in display order is used as a reference picture. Then,motion estimation is performed on the current picture corresponding tothe reference picture to estimate a motion vector. Then, a differencebetween prediction image data generated by motion compensation based onthe estimated motion vector and image data of the current picture isobtained to remove a redundancy in a temporal direction. Here, in themotion estimation, a difference value between the current block in acurrent picture and a block in the reference picture is calculated, anda block having the smallest difference value in the reference picture isdetermined as a reference block. Then, by using the current block andthe reference block, a motion vector is estimated.

In the moving picture coding scheme known as H.264 that has already beenstandardized, in order to compress an information amount, three picturetypes of I picture, P picture, and B picture are used. I picture is apicture on which inter prediction coding is not performed, in otherwords, on which intra-picture prediction (hereinafter, referred to as“intra prediction”) coding is performed. P picture is a picture on whichinter prediction coding is performed with reference to one coded picturelocated prior or subsequent to the current picture in display order. Bpicture is a picture on which inter prediction coding is performed withreference to two coded pictures located prior or subsequent to thecurrent picture in display order.

In the inter prediction coding, a reference picture list for specifyinga reference picture is generated. The reference picture list is a listin which a coded reference picture to be referred to in inter predictionis assigned with a corresponding value(s) of a reference picture index.For example, since a B picture can be coded with reference to twopictures, a B picture has two reference picture lists (L0, L1).

FIG. 1A is a diagram for explaining assignment of reference pictureindexes for each of reference pictures. FIGS. 1B and 1C show an exampleof a pair of reference picture lists for a B picture. In FIG. 1A, forexample, it is assumed that a reference picture 2, a reference picture1, a reference picture 0, and a current picture to be coded are arrangedin display order. Under the assumption, the reference picture list 0(L0) is an example of a reference picture list in a prediction direction0 (the first prediction direction) for bi-directional prediction. Asshown in FIG. 1B, a value “0” of a reference picture index 0 is assignedto the reference picture 0 arranged in the display order 2, a value “1”of the reference picture index 0 is assigned to the reference picture 1arranged in the display order 1, and a value “2” of the referencepicture index 0 is assigned to the reference picture 2 arranged in thedisplay order 0. In short, a greater value of the reference pictureindex is assigned to a picture temporally closer to the current picturein the display order. On the other hand, the reference picture list 1(L1) is an example of a reference picture list in a prediction direction1 (the second prediction direction) for bi-directional prediction. Inthe reference picture list 1 (L1), a value “0” of a reference pictureindex 1 is assigned to the reference picture 1 arranged in the displayorder 1, a value “1” of the reference picture index 1 is assigned to thereference picture 0 arranged in the display order 2, and a value “2” ofthe reference picture index 1 is assigned to the reference picture 2arranged in the display order 0. As described above, for each ofreference pictures, it is possible to assign different reference pictureindexes to respective prediction directions (the reference pictures 0and 1 in FIG. 1A), or assign the same reference picture index to bothprediction directions (reference picture 2 in FIG. 1A).

Furthermore, in the moving picture coding method scheme known as H.264(see Non-Patent Literature 1), as an inter prediction coding mode foreach current block in a B picture, there is a motion vector estimationmode of coding (a) a difference value between prediction image data andimage data of a current block and (b) a motion vector used in generatingthe prediction image data. At the motion vector estimation mode, eitherbi-directional prediction or one-directional prediction is selected. Inthe bi-directional prediction, a prediction image is generated withreference to two coded pictures located prior or subsequent to thecurrent picture. On the other hand, in the one-directional prediction, aprediction image is generated with reference to one coded picturelocated prior or subsequent to the current picture.

Moreover, in the moving picture coding scheme known as H.264, in codingof a B picture, when motion vectors are to be derived, it is possible toselect a coding mode called a temporal prediction motion vector mode.The inter prediction coding method at the temporal prediction motionvector mode is described with reference to FIG. 2. FIG. 2 is anexplanatory diagram showing motion vectors at the temporal predictionmotion vector mode, and shows the situation where a block “a” in apicture B2 is coded at the temporal prediction motion vector mode. Inthis situation, a motion vector vb is used. The motion vector vb hasbeen used to code a block “b” in a picture P3 that is a referencepicture located subsequent to the picture B2. The block “b”(hereinafter, referred to as a “co-located block”) is located, in thepicture P3, at a position corresponding to the position of the block“a”. The motion vector vb is a motion vector that has been used to codethe block “b”, and refers to a picture P1. By using a motion vector inparallel to the motion vector vb, the block “a” obtains reference blocksfrom the picture P1 that is a forward reference picture and from thepicture P3 that is a backward reference picture. Thereby, bi-directionalprediction is performed to code the block “a”. More specifically, themotion vectors used to code the block “a” are a motion vector vatregarding the picture PI and a motion vector vat regarding the pictureP3.

CITATION LIST Patent Literature

-   NPL-1: ITU-T Recommendation H. 264, “Advanced video coding for    generic audiovisual services”, March 2010.

SUMMARY OF INVENTION Technical Problem

However, conventionally, there is a situation where, in coding a currentblock, the selection of either bi-directional prediction orone-directional prediction causes decrease of coding efficiency.

One non-limiting and exemplary embodiment of the present disclosureprovides a moving picture coding method and a moving picture decodingmethod which are capable of improving coding efficiency.

Solution to Problem

In one general aspect, the techniques disclosed here feature; a movingpicture coding method of coding a current block, by copying at least onereference picture index value and at least one motion vector, the atleast one reference picture index value being for specifying a referencepicture that has been used in coding a block different from the currentblock, the moving picture coding method including: specifying aplurality of first candidate blocks from which the at least onereference picture index value and the at least one motion vector are tobe copied; generating a second candidate block that uses bi-directionalprediction, by combining reference picture index values and motionvectors which haven been used for at least part of the first candidateblocks; selecting, from the first candidate blocks and the secondcandidate block, a block from which the at least one reference pictureindex value and the at least one motion vector are to be copied to codethe current block; and copying the at least one reference picture indexvalue and the at least one motion vector from the selected block, andcoding the current block using the copied at least one reference pictureindex value and the copied at least one motion vector.

Thereby, it is possible to code the current picture using motionvector(s) and reference picture(s) which are the most appropriate forthe current block. As a result, coding efficiency can be improved.

For example, it is possible that the generating of the second candidateblock includes: determining whether or not each of the first candidateblocks has one or more reference picture index value and one or moremotion vector; and generating the second candidate block, when at leastone of the first candidate blocks does not have any reference pictureindex value and any motion vector.

For example, it is possible that the moving picture coding methodfurther includes: determining whether or not the current block is to becoded by using the at least one reference picture index value and the atleast one motion vector which are copied from one of the first candidateblocks or the second candidate block; setting a flag indicating a resultof the determining; and adding the flag to a bitstream including thecurrent block.

For example, it is possible that the moving picture coding methodfurther includes: specifying a block index value corresponding to theselected block from which the at least one reference picture index valueand the at least one motion vector are to be copied to code the currentblock, from a candidate list in which the first candidate blocks and thesecond candidate block are assigned with respective block index values;and adding the specified block index value to a bitstream including thecurrent block.

For example, it is possible that the generating of the second candidateblock includes: determining whether or not two of the first candidateblocks have reference picture index values indicating differentprediction directions and have been coded by bi-directional prediction;and generating the second candidate block, when the two of the firstcandidate blocks have different prediction directions or have been codedby bi-directional prediction.

For example, it is possible that the generating of the second candidateblock further includes: determining whether or not one of the two of thefirst candidate blocks has been predicted in a first predictiondirection or coded by bi-directional prediction, and the other one ofthe two of the first candidate blocks has been predicted in a secondprediction direction or coded by bi-directional prediction; and when itis determined that the one of the two of the first candidate blocks hasbeen predicted in the first prediction direction or coded bybi-directional prediction, and the other one of the two of the firstcandidate blocks has been predicted in the second prediction directionor coded by bi-directional prediction, generating the second candidateblock by (i) selecting a reference picture index value and a motionvector which have been used in the first prediction direction for theone of the two of the first candidate blocks, as a reference pictureindex value and a motion vector which are used in the first predictiondirection for the second candidate block, and (ii) selecting a referencepicture index value and a motion vector which have been used in thesecond prediction direction for the other one of the two of the firstcandidate blocks, as a reference picture index value and a motion vectorwhich are used in the second prediction direction for the secondcandidate block.

For example, it is possible that the generating of the second candidateblock further includes: determining whether or not one of the two of thefirst candidate blocks has been predicted in a first predictiondirection or coded by bi-directional prediction, and the other one ofthe two of the first candidate blocks has been predicted in a secondprediction direction or coded by bi-directional prediction; and when itis NOT determined that the one of the two of the first candidate blockshas been predicted in the first prediction direction or coded bybi-directional prediction, and the other one of the two of the firstcandidate blocks has been predicted in the second prediction directionor coded by bi-directional prediction, generating the second candidateblock by (i) selecting a reference picture index value and a motionvector which have been used in the first prediction direction for theother one of the two of the first candidate blocks, as a referencepicture index value and a motion vector which are used in the firstprediction direction for the second candidate block, and (ii) selectinga reference picture index value and a motion vector which have been usedin the second prediction direction for the one of the two of the firstcandidate blocks, as a reference picture index value and a motion vectorwhich are used in the second prediction direction for the secondcandidate block.

In another aspect, the techniques disclosed here feature; a movingpicture decoding method of decoding a current block, by copying at leastone reference picture index value and at least one motion vector, the atleast one reference picture index value being for specifying a referencepicture that has been used in decoding a block different from thecurrent block, the moving picture decoding method including: specifyinga plurality of first candidate blocks from which the at least onereference picture index value and the at least one motion vector are tobe copied; generating a second candidate block that uses bi-directionalprediction, by combining reference picture index values and motionvectors which haven been used for at least part of the first candidateblocks; selecting, from the first candidate blocks and the secondcandidate block, a block from which the at least one reference pictureindex value and the at least one motion vector are to be copied todecode the current block; and copying the at least one reference pictureindex value and the at least one motion vector from the selected block,and decoding the current block using the copied at least one referencepicture index value and the copied at least one motion vector.

Thereby, it is possible to decode a coded bitstream using the mostappropriate motion vector(s) and the most appropriate referencepicture(s).

For example, it is possible that the generating of the second candidateblock includes: determining whether or not each of the first candidateblocks has a reference picture index value and a motion vector; andgenerating the second candidate block, when at least one of the firstcandidate blocks does not have any reference picture index value and anymotion vector.

For example, it is possible that the moving picture decoding methodfurther includes: obtaining, from a bitstream including the currentblock, a flag indicating whether or not the current block is to bedecoded by using the at least one reference picture index value and theat least one motion vector which are copied from one of the firstcandidate block or the second candidate block; and decoding the currentblock according to the flag.

For example, it is possible that the moving picture decoding methodfurther includes: obtaining a block index value from a bitstreamincluding the current block; and selecting, by using the obtained blockindex value, a block from which the at least one reference picture indexvalue and the at least one motion vector are to be copied to decode thecurrent block, from a candidate list in which the first candidate blocksand the second candidate block are assigned with respective block indexvalues.

For example, it is possible that the generating of the second candidateblock includes: determining whether or not two of the first candidateblocks have reference picture index values indicating differentprediction directions and have been coded by bi-directional prediction;and generating the second candidate block, when the two of the firstcandidate blocks have different prediction directions or have been codedby bi-directional prediction.

For example, it is possible that the generating of the second candidateblock further includes: determining whether or not one of the two of thefirst candidate blocks has been predicted in a first predictiondirection or coded by bi-directional prediction, and the other of thetwo of the first candidate blocks has been predicted in a secondprediction direction or coded by bi-directional prediction; and when itis determined that the one of the two of the first candidate blocks hasbeen predicted in the first prediction direction or coded bybi-directional prediction, and the other of the two of the firstcandidate blocks has been predicted in the second prediction directionor coded by bi-directional prediction, generating the second candidateblock by (i) selecting a reference picture index value and a motionvector which have been used in the first prediction direction for theone of the two of the first candidate blocks, as a reference pictureindex value and a motion vector which are used in the first predictiondirection for the second candidate block, and (ii) selecting a referencepicture index value and a motion vector which have been used in thesecond prediction direction for the other one of the two of the firstcandidate blocks, as a reference picture index value and a motion vectorwhich are used in the second prediction direction for the secondcandidate block.

It should be noted that the present disclosure can be implemented notonly as the above moving picture coding method and moving picturedecoding method, but also as: a moving picture coding apparatus, amoving picture decoding apparatus, and a moving picture coding anddecoding apparatus each of which includes processing units performingthe characterized steps included in the moving picture coding method andmoving picture decoding method; a program causing a computer to executethe steps; and the like. The present disclosure can be implemented alsoas: a computer-readable recording medium, such as a Compact Disc-ReadOnly Memory (CD-ROM), on which the above program is recorded;information, data, signals indicating the program; and the like. Theprogram, information, data, or signals can be distributed via atransmission medium such as the Internet.

Advantageous Effects of Invention

According to the present disclosure, a new merge block candidate ofbi-directional prediction is calculated from merge block candidates, soas to improve coding efficiency.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present invention. In the Drawings:

FIG. 1A is a diagram for explaining assignment of reference pictureindexes for each of reference pictures;

FIG. 1B is a table showing an example of one of reference picture listsfor a B picture;

FIG. 1C is a table showing an example of the other reference picturelist for a B picture;

FIG. 2 is an exemplary diagram showing motion vectors at the temporalprediction motion vector mode;

FIG. 3A is a diagram showing a relationship among: a current block to becoded; neighbor blocks; and motion vectors of the neighbor blocks;

FIG. 3B is a table showing an example of a merge block candidate list inwhich each value of a merge index is assigned to a motion vector and areference picture index which are to be used at the merge mode;

FIG. 4 is a block diagram showing a structure of a moving picture codingapparatus using a moving picture coding method according to anembodiment of the present disclosure;

FIG. 5 is a flowchart of a summary of a processing flow of the movingpicture coding method according to the embodiment of the presentdisclosure;

FIG. 6 is a table showing an example of a merge block candidate list inwhich each value of a merge index is assigned to a motion vector and areference picture index which are to be used at the merge mode accordingto Embodiment 1;

FIG. 7 is an example of a coding table which is used to perform variablelength coding on the merge block index;

FIG. 8 is a flowchart of a detailed processing flow for calculating acombined merge block;

FIG. 9 is a flowchart of a detailed processing flow for comparingprediction errors;

FIG. 10 is a block diagram showing a structure of a moving picturedecoding apparatus using a moving picture decoding method according toan embodiment of the present disclosure;

FIG. 11 is a flowchart of a summary of a processing flow of a movingpicture decoding method according to an embodiment of the presentdisclosure;

FIG. 12 shows an overall configuration of a content providing system forimplementing content distribution services;

FIG. 13 shows an overall configuration of a digital broadcasting system;

FIG. 14 shows a block diagram illustrating an example of a configurationof a television;

FIG. 15 shows a block diagram illustrating an example of a configurationof an information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk;

FIG. 16 shows an example of a configuration of a recording medium thatis an optical disk;

FIG. 17A shows an example of a cellular phone;

FIG. 17B is a block diagram showing an example of a configuration of acellular phone;

FIG. 18 illustrates a structure of multiplexed data;

FIG. 19 schematically shows how each stream is multiplexed inmultiplexed data;

FIG. 20 shows how a video stream is stored in a stream of PES packets inmore detail;

FIG. 21 shows a structure of TS packets and source packets in themultiplexed data;

FIG. 22 shows a data structure of a PMT;

FIG. 23 shows an internal structure of multiplexed data information;

FIG. 24 shows an internal structure of stream attribute information;

FIG. 25 shows steps for identifying video data;

FIG. 26 shows an example of a configuration of an integrated circuit forimplementing the moving picture coding method and the moving picturedecoding method according to each of Embodiments;

FIG. 27 shows a configuration for switching between driving frequencies;

FIG. 28 shows steps for identifying video data and switching betweendriving frequencies;

FIG. 29 shows an example of a look-up table in which video datastandards are associated with driving frequencies;

FIG. 30A is a diagram showing an example of a configuration for sharinga module of a signal processing unit; and

FIG. 30B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS

In the moving picture coding scheme, a coding mode called a merge modehas been examined as an inter prediction mode for each block to be codedin a B picture or a P picture. At this merge mode, a motion vector and avalue of a reference picture index (hereinafter, referred to also as“reference picture index values”) are copied from a neighbor block of acurrent block to be coded, so as to code the current block. Here, byadding the index value and the like of the neighbor block from whichthey are copied are added into a bitstream. As a result, a motion vectoror a value of reference picture index which have been used in coding canbe selected in decoding. A detailed example is described with referenceto corresponding figures.

FIG. 3A is a diagram showing a relationship among: a current block to becoded; neighbor blocks; and motion vectors of the neighbor blocks. FIG.3B is a table showing an example of a merge block candidate list inwhich each value of a merge index is assigned to a motion vector and areference picture index which are to be used at the merge mode.

In FIG. 3A, a coded block at the immediately left of the current blockis referred to as a neighbor block A, a coded block immediately abovethe current block is referred to as a neighbor block B, a coded block atthe immediately upper right of the current block is referred to as aneighbor block C, and a coded block at the immediately lower left of thecurrent block is referred to as a neighbor block D. Furthermore, in FIG.3A, the neighbor block A has been coded by one-directional predictionusing a prediction direction 0 (the first prediction direction). Theneighbor block A has a motion vector MvL0_A of the prediction direction0 for a reference picture indicated by an index value RefL0_A in areference picture index of the prediction direction 0. Here, the motionvector MvL0 is a motion vector referring to a reference picturespecified by the reference picture list 0 (L0), and MvL1 is a motionvector referring to a reference picture specified by the referencepicture list 1 (L1). The neighbor block B has been coded byone-directional prediction using a prediction direction 1 (the secondprediction direction). The neighbor block B has a motion vector MvL1_Bof the prediction direction 1 for a reference picture indicated by anindex value RefL1_B in a reference picture index of the predictiondirection 1. The neighbor block C has been coded by intra prediction.The neighbor block D has been coded by one-directional prediction usingthe prediction direction 0. The neighbor block D has a motion vectorMvL0_D of the prediction direction 0 for a reference picture indicatedby an index value RefL0_D in the reference picture index of theprediction direction 0.

In the situation as shown in FIG. 3A, as a motion vector and a referencepicture index value for the current block, a motion vector and areference picture index value which offer the highest coding efficiencyare selected, for example, from (a) the motion vectors and the referencepicture index values of the neighbor blocks A, B, C, and D, and (b) amotion vector and a reference picture index value of the co-locatedblock which are obtained at the temporal prediction motion vector mode.Then, a merge block index indicating the selected neighbor block orco-located block is added into the bitstream. For example, if theneighbor block A is selected, the current block is coded by using themotion vector MvL0_A and the reference picture index value ReL0_A of theprediction direction 0, and only a value “0” of the merge block indexindicating that the neighbor block A is used as shown in FIG. 3B isadded into the bitstream, so that an information amount of motionvectors and reference picture index values can be reduced.

However, at the above-described merge mode, if a block to be a mergeblock candidate does not have any motion vector and reference pictureindex value because the block has been coded by intra prediction (likethe neighbor block C), the block cannot be used as a merge blockcandidate. In the above situation, it is also considered that the numberof available merge block candidates is decreased, the selection rangefor a motion vector and a reference picture index value which offer thehighest coding efficiency is reduced, and eventually coding efficiencyis decreased.

In order to address the above problem, one non-limiting and exemplaryembodiment provides an image coding method and an image decoding methodwhich are capable of improving coding efficiency without decreasing thenumber of available merge block candidates at the merge mode.

The following describes embodiments according to the present disclosurewith reference to the drawings. It should be noted that all theembodiments described below are specific examples of the presentdisclosure. Numerical values, shapes, materials, constituent elements,arrangement positions and the connection configuration of theconstituent elements, steps, the order of the steps, and the likedescribed in the following embodiments are merely examples, and are notintended to limit the present disclosure. The present disclosure ischaracterized only by the appended claims. Therefore, among theconstituent elements in the following embodiments, constituent elementsthat are not described in independent claims that show the most genericconcept of the present disclosure are described as elements constitutingmore desirable configurations, although such constituent elements arenot necessarily required to achieve the object of the presentdisclosure.

Embodiment 1

FIG. 4 is a block diagram showing a structure of a moving picture codingapparatus using a moving picture coding method according to Embodiment1.

As shown in FIG. 4, the moving picture coding apparatus 100 includes anorthogonal transformation unit 101, a quantization unit 102, an inversequantization unit 103, an inverse orthogonal transformation unit 104, ablock memory 105, a frame memory 106, an intra prediction unit 107, aninter prediction unit 108, an inter prediction control unit 109, apicture type determination unit 110, a merge block candidate calculationunit 111, a colPic memory 112, a variable length coding unit 113, asubtractor 114, an adder 115, and a switch unit 116.

The orthogonal transformation unit 101 transforms prediction error datathat is a difference between prediction data generated as describedbelow and an input image sequence, from an image domain to a frequencydomain. The quantization unit 102 quantizes the prediction error datathat has been transformed in the frequency domain. The inversequantization unit 103 inversely quantizes the prediction error data thathas been quantized by the quantization unit 102. The inverse orthogonaltransformation unit 104 transforms the inversely-quantized predictionerror data from a frequency domain to an image domain. The adder 115adds the prediction data to the inversely-quantized prediction errordata to generate a decoded data. The block memory 105 holds the decodedimage on a block-by-block basis. The frame memory 106 holds the decodedimage on a picture-by-picture basis. The picture type determination unit110 determines by which picture type from among an I picture, a Bpicture, or a P picture, each picture in the input image sequence is tobe coded, and generates picture type information. The intra predictionunit 107 codes a current block to be coded by intra prediction, by usingthe decoded image stored on a block-by-block basis in the block memory105, so as to generate prediction picture. The inter prediction unit 108codes the current block by inter prediction by using the decoded imagestored on a picture-by-picture basis in the frame memory 106 and amotion vector derived in motion estimation, so as to generate predictionpicture. The subtractor 114 subtracts the prediction data generated bythe intra prediction unit 206 or the inter prediction unit 207 from theinput image sequence, so as to calculate prediction error data.

The merge block candidate calculation unit 111 specifies merge blockcandidates (the first candidate blocks) of the merge mode, by using (a)motion vectors and reference picture index values which have been usedto code the neighbor blocks and (b) colPic information such as a motionvector and the like of the co-located block which is stored in thecolPic memory 112 regarding the current block. Here, the merge blockcandidates are candidates of a block from which at least one motionvector and at least one reference picture index value are directly used(copied) for the current block. In addition, the merge block candidatecalculation unit 111 generates a combined merge block (the secondcandidate block) by the method described below. It should be noted thatthe combined merge block is not a block actually having pixel values,but a virtual block having motion vectors and reference picture indexvalues. Furthermore, the merge block candidate calculation unit 111assigns each of the specified merge blocks with a corresponding value ofthe merge block index (block index). Then, the merge block candidatecalculation unit 111 provides the merge block candidates and the valuesof the merge block index (hereinafter, referred to also as “merge blockindex values”) to the inter prediction control unit 109. It should benoted in the present embodiment 1 that the motion vectors and thereference picture index values used for the neighbor blocks of thecurrent picture are assumed to be stored in the merge block candidatecalculation unit 111.

The inter prediction control unit 109 performs inter prediction codingat a prediction mode having the smallest prediction error between (a) aprediction mode for an inter prediction image generated by using amotion vector derived by the motion estimation mode and (b) a predictionmode for an inter prediction image generated by using a motion vectorderived at the merge mode. Moreover, the inter prediction control unit109 provides the variable length coding unit 113 with (a) a merge flagindicating whether or not the prediction mode is the merge mode, (b) amerge block index value corresponding to the determined merge block ifthe merge mode is selected as the prediction mode, and (c) predictionerror information. Furthermore, the inter prediction control unit 109transfers colPic information including the motion vector and the likefor the current block, to the colPic memory 112.

The variable length coding unit 113 performs variable length coding onthe quantized prediction error data, merge flag, merge block indexvalue, and picture type information, so as to generate a bitstream.

FIG. 5 is a flowchart of a summary of a processing flow of the movingpicture coding method according to the present embodiment.

The merge block candidate calculation unit 111 specifies merge blockcandidates from neighbor blocks and a co-located block of a currentblock to be coded (Step S11). For example, in the situation shown inFIG. 3A, the merge block candidate calculation unit 111 specifies theneighbor blocks A, B, C, D, and a co-located merge block, as merge blockcandidates. Here, the co-located merge block includes at least onemotion vector and the like which are calculated at the temporalprediction mode from at least one motion vector of the co-located block.Then, the merge block candidate calculation unit 111 assigns each of themerge block candidates with a corresponding value of the merge blockindex as shown in FIG. 3B. In general, as a value of the merge blockindex is smaller, a necessary information amount is decreased. On theother hand, as a value of the merge block index is larger, a necessaryinformation amount is increased. Therefore, if a merge block index valuecorresponding to a merge block candidate having a high possibility ofhaving a more accurate motion vector and a more accurate referencepicture index value is decreased, coding efficiency is increased. Forexample, it can be considered that how many times each merge blockcandidate has been selected as a merge block is counted, and a smallervalue of the merge block index is assigned to a block having the greatercounts. Here, if a target merge block candidate does not holdinformation such as a motion vector, for example, if the merge blockcandidate is a block coded by intra prediction, or if the merge blockcandidate is located outside a picture boarder or a slice boarder, it isassumed that such a block cannot be used as a merge block candidate. Inthe present embodiment, if a block cannot be used as a merge blockcandidate, the block is referred to as a non-available block, and if ablock can be used as a merge block candidate, the block is referred toas an available block. In the situation shown in FIG. 3A, since theneighbor block C is a block coded by intra prediction, the neighborblock C is considered as not being available as a non-available block asa merge block candidate.

By using the merge block candidates specified at S11, the merge blockcandidate calculation unit 111 generates a combined merge block by themethod as described later, so as to update the merge block candidatelist (Step S12). For example, the merge block candidate list shown inFIG. 6 is generated from the merge block candidate list shown in FIG.3B. In the merge block candidate list in FIG. 3B, the combined mergeblock generated by the method described later is used instead of anon-available candidate having a value “3” of the merge block index. Byusing such a newly generated combined merge block instead of thenon-available candidate, it is possible to improve coding efficiencywithout changing a maximum value of the number of merge blockcandidates.

Next, the inter prediction control unit 109 compares (a) the predictionerror of the inter prediction image generated by using the motion vectorderived by motion estimation to (b) the prediction error of theprediction image generated by the merge block candidate by the methoddescribed later, so as to determine a prediction mode for coding thecurrent block. Here, if it is determined that the prediction mode is themerge mode, then the inter prediction control unit 109 determines avalue of the merge block index indicating which merge block candidate isto be used. Then, if the prediction mode is the merge mode, then theinter prediction control unit 109 sets the merge flag to 1, otherwise,sets the merge flag to 0 (Step S13). The inter prediction control unit109 determines whether or not the merge flag is 1, in other words,whether or not the prediction mode is the merge mode (Step S14). As aresult, if the prediction mode is the merge mode (Yes at Step S14), thenthe inter prediction control unit 109 provides the variable lengthcoding unit 113 with the merge flag and the merge block index value tobe used for the merge, so as to add the merge flag and the index valueinto a bitstream (Step S15). On the other hand, if the prediction modeis not the merge mode (No at Step S14), then the inter predictioncontrol unit 109 provides the variable length coding unit 113 with themerge flag and information of the motion estimation vector mode, so asto add the merge flag and the information into the bitstream (Step S16).

It should be noted in the present embodiment that, as shown in FIG. 3B,regarding the merge block index values, a value corresponding to theneighbor block A is “0”, a value corresponding to the neighbor block Bis “1”, a value corresponding to the co-located merge block is “2”, avalue corresponding to the neighbor block C is “3”, and a valuecorresponding to the neighbor block D is “4”. However, the way ofassigning values of the merge block index is not limited only to theexample. For instance, it is also possible that the largest value isassigned to a non-available candidate as a merge block candidate. Itshould also be noted that the merge block candidates are not limited tothe neighbor blocks A, B, C, and D. For example, a neighbor block or thelike that is located above the immediately-lower-left block D may beselected as a merge block candidate. It should also be noted that it isnot necessary to use all of the neighbor blocks, but only the neighborblocks A and B may be used as the merge block candidates. It should alsobe noted that it is not necessary to always use the co-located mergeblock.

It should also be noted that it has been described in the presentembodiment at S15 in FIG. 5 that the inter prediction control unit 109provides a value of the merge block index to the variable length codingunit 113 so as to add the merge block index value into the bitstream,but it is also possible not to add the merge block index value if thenumber of the merge block candidates is 1. Thereby, it is possible toreduce an information amount of the merge block index.

It should also be noted that it has been described in the presentembodiment at S12 in FIG. 5 that a combined merge block is used insteadof a non-available candidate having a value “3” of the merge blockindex. However, the present disclosure is not limited to the above andthe combined merge block may be further added in the merge blockcandidate list. Thereby, it is possible to increase the selection rangeof the merge block candidates. Here, it is also possible that thenon-available candidate is treated as a candidate having the motionvector 0 and the reference picture index 0.

FIG. 7 shows an example of a coding table which is used to performvariable length coding on merge block index values.

In the example shown in FIG. 7, a code having a shorter code length isassigned to a smaller value of the merge block index. Therefore, if amerge block index value corresponding to a merge block candidate havinga possibility of a high prediction accuracy is decreased, it is possibleto improve coding efficiency.

It should be noted that it has been described in the present embodimentthat variable length coding is performed on merge block index values asshown in FIG. 7, but the merge block index values may be coded with afixed code length. Thereby, it is possible to reduce a load on coding ordecoding processing.

FIG. 8 is flowchart of a detailed flow of S12 in FIG. 5. The followingdescribes the method of generating a combined merge block from the mergeblock candidates specified at S11 with reference to FIG. 8.

The merge block candidate calculation unit 111 initializes an indexvalue 1 (idx1) to “0” (Step S21). Then, the merge block candidatecalculation unit 111 initializes an index value 2 (idx2) to “0” (StepS22). The merge block candidate calculation unit 111 determines whetheror not the idx1 and the idx2 have different values and the merge blockcandidate list includes any non-available candidate (Step S23). As aresult, if there is a non-available candidate (Yes at Step S23), thenthe merge block candidate calculation unit 111 determines whether or notthe merge block candidate [idx1] assigned with the merge block indexvalue idx1 is available and the merge block candidate [idx2] assignedwith the merge block index value idx2 is available (Step S24). As aresult, if the merge block candidate [idx1] is available and the mergeblock candidate [idx2] is also available (Yes at Step S24), then themerge block candidate calculation unit 111 determines whether or not themerge block candidate [idx1] and the merge block candidate[idx2] havebeen predicted in different prediction directions, or both the mergeblock candidate [idx1] and the merge block candidate [idx2] have beencoded by bi-directional prediction (Step S25). As a result, if the mergeblock candidate [idx1] and the merge block candidate[idx2] have beenpredicted in different prediction directions, or both the merge blockcandidate [idx1] and the merge block candidate [idx2] have been coded bybi-directional prediction (Yes at Step S25), then the merge blockcandidate calculation unit 111 determines whether or not the merge blockcandidate [idx1] has been predicted in the prediction direction 0 (thefirst prediction direction) or coded by the bi-directional prediction,and the merge block candidate [idx2] has been predicted in theprediction direction 1 (the second prediction direction) or coded by thebi-directional prediction (Step S26). As a result, if the merge blockcandidate [idx1] has been predicted in the prediction direction 0 orcoded by the bi-directional prediction, and the merge block candidate[idx2] has been predicted in the prediction direction 1 or coded by thebi-directional prediction (Yes at Step S26), in other words, if themerge block candidate [idx1] has at least a motion vector of theprediction direction 0 and the merge block candidate [idx2] has at leasta motion vector of the prediction direction 1, then the merge blockcandidate calculation unit 111 selects the motion vector and thereference picture index value of the prediction direction 0 of the mergeblock candidate [idx1] for the prediction direction 0 of the combinedmerge block (Step S27). In addition, the merge block candidatecalculation unit 111 selects the motion vector and the reference pictureindex value of the prediction direction 1 of the merge block candidate[idx2] for the prediction direction 1 of the combined merge block, so asto generate the combined merge block of bi-directional prediction (StepS28). On the other hand, if it is not determined that the merge blockcandidate [idx1] has been predicted in the prediction direction 0 orcoded by the bi-directional prediction, and the merge block candidate[idx2] has been predicted in the prediction direction 1 or coded by thebi-directional prediction (No at Step S26), then the merge blockcandidate calculation unit 111 selects the motion vector and thereference picture index value of the prediction direction 0 of the mergeblock candidate [idx2] for the prediction direction 0 of the combinedmerge block (Step S29). In addition, the merge block candidatecalculation unit 111 selects the motion vector and the reference pictureindex value of the prediction direction 1 of the merge block candidate[idx1] for the prediction direction 1 of the combined merge block, so asto generate the combined merge block of bi-directional prediction (StepS30). The merge block candidate calculation unit 111 adds the generatedcombined merge block into the merge block candidate list as an availablecandidate, instead of the non-available candidate (Step S31). Next, themerge block candidate calculation unit 111 adds a value “1” to the valueidx2 (Step S32), and determines whether or not the value idx2 is equalto or greater than the maximum value of the number of the merge blockcandidates (Step S33). As a result, if the value idx2 is not equal to orgreater than the maximum value of the number of the merge blockcandidates (No at Step S33), the processing returns to Step S23, thenthe merge block candidate calculation unit 111 determines again whetheror not any non-available candidate remains, and generates a nextcombined merge block (Steps S23 to S32). On the other hand, if the valueidx2 is equal to or greater than a maximum value of the number of themerge block candidates (Yes at Step S33), then the merge block candidatecalculation unit 111 adds a value “1” to the idx1 (Step S34) anddetermines whether or not the idx1 is equal to or greater than themaximum value of the number of the merge block candidates (Step S35). Asa result, if the idx1 is equal to or greater than the maximum value ofthe number of the merge block candidates (Yes at Step S35), in otherwords, if every combination of the merge block candidates has beenexamined, the processing is completed.

It should be noted that it has been described in the present embodimentthat the processing is completed when every combination of the mergeblock candidates has been examined, but the present disclosure is notlimited to the above. For example, it is possible to complete theprocessing when there is no more non-available candidate in the mergeblock candidate list. As a result, a processing amount can be reduced.

It should also be noted that it has been described in the presentembodiment that the steps in the method of generating a combined mergeblock from merge block candidates are performed in the order shown inthe flowchart of FIG. 8, but the present disclosure is not limited tothe above and the order of the steps may be changed.

It should also be noted that it has been described in the presentembodiment that, for example, when a motion vector and a referencepicture index value of the prediction direction regarding a neighborblock is selected for the prediction direction 0 of the combined mergeblock, if there are a plurality of merge block candidates having amotion vector and a reference picture index value of the predictiondirection 0, the motion vector and the reference picture index value ofthe prediction direction 0 which are regarding the merge block candidatehaving the merge block index value that is closer to “0” is selected.However, the present disclosure is not limited to the above. Forexample, it is also possible to select a motion vector and a referencepicture index value of the prediction direction 0 which are regarding amerge block candidate having a merge block index value that is closer toa maximum value.

It should also be noted that it has been described in the presentembodiment at S31 in FIG. 8 that the generated combined merge block isadded to the merge block candidate list as an available candidateinstead of a non-available candidate, but the present disclosure is notlimited to the above. For example, it is also possible that it isdetermined whether or not any other merge block candidate holding thesame motion vector and the same value of the reference picture index asthose of the combined merge block is already included in the merge blockcandidate list, and if there is no such a candidate in the list, thecombined merge block is added to the merge block candidate list as anavailable candidate instead of a non-available candidate. Thereby, bypreventing that the same merge block candidate is added again, it ispossible to add effective merge block candidates. As a result, codingefficiency can be improved.

It should also be noted that it has been described in the presentembodiment that the generated combined merge block is added to the mergeblock candidate list when there is a non-available candidate in themerge block candidate list, but the present disclosure is not limited tothe above. For example, it is also possible at S23 in FIG. 8 that thedetermination as to whether or not there is a non-available candidate inthe merge block candidate list is not made, but the combined merge blockis calculated and newly added to the merge block candidate list.Thereby, it is possible to increase the selection range of the mergeblock candidates. As a result, coding efficiency can be improved.

FIG. 9 is flowchart of a detailed flow of S13 in FIG. 5. The followingdescribes with reference to FIG. 9.

The inter prediction control unit 109 sets a value of the merge blockcandidate index to “0”, the minimum prediction error to a predictionerror (cost) of the motion vector estimation mode, and the merge flag to“0” (Step S41). Here, the cost is calculated by, for example, thefollowing Equation 1 of the R-D optimization model.Cost=D+λ×R  (Equation 1)

In Equation 1, D represents a coding distortion which is, for example, asum of absolute values of difference of (a) a pixel value obtained bycoding and decoding a current block by using a prediction imagegenerated by a certain motion vector and (b) an original pixel value ofthe current block. Furthermore, R represents a coding amount which is,for example, a coding amount required to code the motion vector used ingenerating the prediction image. A represents a Lagrange's method ofundetermined multipliers.

Then, the inter prediction control unit 109 determines whether or not avalue of the merge block candidate index is smaller than the number ofmerge block candidates of the current block, in other words, whether ornot there is any block having a possibility of being a merge candidate(Step S42). As a result, if it is determined that the value of the mergeblock candidate index is smaller than the number of merge blockcandidates of the current block (Yes at Step S42), then the interprediction control unit 109 calculates a cost of the merge blockcandidate assigned with the value of the merge block candidate index(Step S43). Next, the inter prediction control unit 109 determineswhether or not the calculated cost of the merge block candidate issmaller than the minimum prediction error (Step S44). As a result, ifthe calculated cost of the merge block candidate is smaller than theminimum prediction error (Yes at Step S44), then the inter predictioncontrol unit 109 updates the minimum prediction error, the value of themerge block index, and the value of the merge flag (Step S45). Next, theinter prediction control unit 109 adds a value of “1” to the value ofthe merge block candidate index (Step S46), and the processing repeatsfrom S42 to S46. If the calculated cost of the merge block candidate isnot smaller than the minimum prediction error (No at Step S44), then theupdating process at S45 is not performed but Step 46 is performed, andthe processing repeats from S42 to S46. Here, at Step S42, if the valueof the merge block candidate index is not smaller than the number of themerge block candidates (No at Step S42), in other words, if there is nomerge block candidate, then the inter prediction control unit 109eventually determines the finally left merge flag and the value of themerge block index (Step S47).

According to the present embodiment of the present disclosure, a newmerge block candidate of bi-directional prediction is calculated frommerge block candidates, so as to improve coding efficiency. Morespecifically, based on the merge block candidates calculated from theneighbor blocks and the co-located block, (a) a motion vector and areference picture index value of the prediction direction 0 and (b) amotion vector and a reference picture index value of the predictiondirection 1 are combined to generated a combined merge block ofbi-directional prediction, and then added to the merge block candidatelist. As a result, coding efficiency can be improved. Furthermore, ifthere is a non-available candidate in the merge block candidate list, acombined merge block is generated and the non-available candidate isreplaced by the combined merge block. Thereby, coding efficiency can beimproved without increasing a maximum value of the number of merge blockcandidates.

It should be noted that it has been described in the present embodimentthat the merge flag is always added to a bitstream at the merge mode,but the present disclosure is not limited to the above. For example, itis also possible that it is forced to select the merge mode according toa shape or the like of the current block. In this case, it is possiblethat an information amount is reduced by not adding the merge flag tothe bitstream

It should be noted that it has been described in the present embodimentthat, at the merge mode, at least one motion vector and at least onereference picture index value are copied from a neighbor block of thecurrent block and then used to code the current block, but the presentdisclosure is not limited to the above. For example, the following isalso possible. In the same manner as at the merge mode, by using themerge block candidates generated as shown in FIG. 6, at least one motionvector and at least one reference picture index value are copied from aneighbor block of the current block and then used to code the currentblock. As a result, if every prediction error data of the current blockis 0, a skip flag is set to 1 and added to the bitstream. On the otherhand, if every prediction error data is not 0, the skip flag is set to 0and the skip flag and the prediction error data are added to thebitstream (merge skip mode).

It should also be noted that it has been described in the presentembodiment that, at the merge mode, at least one motion vector and atleast one reference picture index value are copied from a neighbor blockof the current block and then used to code the current block, but thepresent disclosure is not limited to the above. For example, it is alsopossible that a motion vector at the motion vector estimation mode iscoded by using the merge block candidate list generated as shown in FIG.6. More specifically, it is possible that a motion vector of a mergeblock candidate designated by the merge block index value is subtractingfrom the motion vector of the motion vector estimation mode, so as toobtain a difference, and that the difference and the merge blockcandidate index value are added to the bitstream. Furthermore, thefollowing is also possible. By using a reference picture index valueRefIdx_ME of the motion estimation mode and a reference picture indexvalue RefIdx_Merge of the merge block candidate, scaling is performed ona motion vector MV_Merge of the merge block candidate. Then, a motionvector scaledMV_Merge of the scaled merge block candidate is subtractingfrom the motion vectors at the motion estimation mode to obtain adifference. The difference and the value of the merge block candidateindex are added to the bitstream. This scaling can be performed by usingthe following Equation 2.scaledMV_Merge=MV_Merge×(POC(RefIdx_ME)−curPOC)/(POC(RefIdx_Merge)−curPOC)  (Equation2)

Here, POC(RefIdx_ME) represents a location in a display order of areference picture indicated by the reference picture index valueRefIdx_ME, POC(RefIdx_Merge) represents a location in the display orderof a reference picture indicated by the reference picture index valueRefIdx_Merge, and curPOC represents a location in the display order of apicture to be coded

Embodiment 2

FIG. 10 is a block diagram showing a structure of a moving picturedecoding apparatus using a moving picture decoding method according toEmbodiment 2 of the present disclosure.

As shown in FIG. 10, the moving picture decoding apparatus 200 includesa variable length decoding unit 201, an inverse quantization unit 202,an inverse orthogonal transformation unit 203, a block memory 204, aframe memory 205, an intra prediction unit 206, an inter prediction unit207, an inter prediction control unit 208, a merge block candidatecalculation unit 209, a colPic memory 210, an adder 211, and a switch212.

The variable length decoding unit 201 performs variable length decodingon an input bitstream so as to obtain the picture type information, themerge flag, and the merge block index, and a variable-length-decodedbitstream. The inverse quantization unit 202 inversely quantizes thevariable-length-decoded bitstream. The inverse orthogonal transformationunit 203 transforms the inversely-quantized bitstream from a frequencydomain to an image domain, so as to generate prediction error imagedata. The block memory 204 holds an image sequence generated by addingthe prediction error image data to prediction picture on ablock-by-block basis. The frame memory 205 holds the image sequence on apicture-by-picture basis. The intra prediction unit 206 performs intraprediction on the image sequence stored in the block memory 204 on ablock-by-block basis, so as to generate prediction image data of acurrent block to be decoded. The inter prediction unit 207 performsinter prediction on the image sequence stored in the frame memory on apicture-by-picture basis, so as to generate prediction image data of thecurrent block to be decoded.

The merge block candidate calculation unit 209 derives merge blockcandidates of the merge mode, by using colPic information such as motionvectors of neighbor blocks and a co-located block stored in the colPicmemory 210 regarding the current block. In addition, the merge blockcandidate calculation unit 209 assigns each of the derived merge blockswith a corresponding value of the merge block index. Then, the mergeblock candidate calculation unit 209 provides the merge block candidatesand the values of the merge block index to the inter prediction controlunit 208.

If the merge flag decoded by the variable length decoding unit 210 is“0”, in other words, if the prediction mode is not the merge mode, theinter prediction control unit 208 generates inter prediction image usingthe decoded information of motion estimation mode. Furthermore, if themerge flag is “1”, in other words, if the prediction mode is the mergemode, then the inter prediction control unit 208 determines a motionvector and a reference picture index value to be used in interprediction from the plurality of merge block candidates, based on thedecoded merge block index value, so as to generate inter predictionimage. Moreover, the inter prediction control unit 208 provides thecolPic memory 210 with colPic information including the motion vectorand the like of the current block.

The adder 211 adds the prediction data generated by the intra predictionunit 206 or the inter prediction unit 207 to the prediction error dataprovided from the inverse orthogonal transformation unit 203, so as togenerated a decoded image sequence.

FIG. 11 is a flowchart of a summary of a processing flow of the movingpicture decoding method according to the present embodiment.

The variable length decoding unit 201 decodes a merge flag from abitstream (Step S51). The inter prediction control unit 208 determineswhether or not the merge flag is “1” (Step S52). As a result, if themerge flag is “1” (Yes at Step S52), then the merge block candidatecalculation unit 209 specifies merge block candidates from neighborblocks and a co-located block of a current block to be decoded (StepS53). In the same method as shown in FIG. 8, the merge block candidatecalculation unit 209 generates a combined merge block, and updates themerge block candidate list (Step S54). Thereby, likewise the codingprocessing, for example, the merge block candidate list shown in FIG. 6is generated from the merge block candidate list shown in FIG. 3B. Theinter prediction control unit 208 determines a merge block from which atleast one motion vector and at least one reference picture index valueare copied, according to the merge block index value decoded by thevariable length decoding unit 201, and generate inter prediction imageusing the determined merge block (Step S55). On the other hand, at StepS52, if the merge flag is “0”, then the inter prediction control unit208 generates inter prediction image using the information of motionvector estimation mode which is decoded by the variable length decodingunit 201 (Step S56). It should be noted that, if the number of the mergeblock candidates specified or generated at S53 and S54 is one, it ispossible not to decode a value of the merge block index but to estimatethe value of the merge block index as 0.

According to the present embodiment of the present disclosure, a newmerge block of bi-directional prediction is calculated from merge blockcandidates, so as to appropriately decode a bitstream with improvedcoding efficiency.

More specifically, based on the merge block candidates calculated by theneighbor blocks and the co-located block, (a) a motion vector and a thereference picture index value of the prediction direction 0 and (b) amotion vector and a reference picture index value of the predictiondirection 1 are combined to generate a combined merge block ofbi-directional prediction, and added to the merge block candidate list.As a result, it is possible appropriately decode the bitstream withimproved coding efficiency. Furthermore, if there is a non-availablecandidate in the merge block candidate list, a combined merge block iscalculated and the non-available candidate is replaced by the combinedmerge block. Thereby, it is possible appropriately decode the bitstreamwith improved coding efficiency, without increasing a maximum value ofthe number of merge block candidates.

Embodiment 3

The processing described in each of Embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofEmbodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of Embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image encoding apparatus using theimage encoding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 12 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 12, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital video camera, iscapable of capturing both still images and video. Furthermore, thecellular phone ex114 may be the one that meets any of the standards suchas Global System for Mobile Communications (GSM), Code Division MultipleAccess (CDMA), Wideband-Code Division Multiple Access (W-CDMA), LongTerm Evolution (LTE), and High Speed Packet Access (HSPA).Alternatively, the cellular phone ex114 may be a Personal HandyphoneSystem (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of Embodiments (i.e., the camerafunctions as the image coding apparatus of the present invention), andthe coded content is transmitted to the streaming server ex103. On theother hand, the streaming server ex103 carries out stream distributionof the transmitted content data to the clients upon their requests. Theclients include the computer ex111, the PDA ex112, the camera ex113, thecellular phone ex114, and the game machine ex115 that are capable ofdecoding the above-mentioned coded data. Each of the devices that havereceived the distributed data decodes and reproduces the coded data(i.e., the devices each function as the image decoding apparatus of thepresent invention).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the image data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of Embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 13. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of Embodiments (i.e.,data coded by the image coding apparatus of the present invention). Uponreceipt of the multiplexed data, the broadcast satellite ex202 transmitsradio waves for broadcasting. Then, a home-use antenna ex204 with asatellite broadcast reception function receives the radio waves. Next, adevice such as a television (receiver) ex300 and a set top box (STB)ex217 decodes the received multiplexed data, and reproduces the decodeddata (i.e., the device functions as the image coding apparatus of thepresent invention).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording media ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of Embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 14 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of Embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, (which function as the image coding apparatusand the image decoding apparatus), respectively; and an output unitex309 including a speaker ex307 that provides the decoded audio signal,and a display unit ex308 that displays the decoded video signal, such asa display. Furthermore, the television ex300 includes an interface unitex317 including an operation input unit ex312 that receives an input ofa user operation. Furthermore, the television ex300 includes a controlunit ex310 that controls overall each constituent element of thetelevision ex300, and a power supply circuit unit ex311 that suppliespower to each of the elements. Other than the operation input unitex312, the interface unit ex317 may include: a bridge ex313 that isconnected to an external device, such as the reader/recorder ex218; aslot unit ex314 for enabling attachment of the recording medium ex216,such as an SD card; a driver ex315 to be connected to an externalrecording medium, such as a hard disk; and a modem ex316 to be connectedto a telephone network. Here, the recording medium ex216 canelectrically record information using a non-volatile/volatilesemiconductor memory element for storage. The constituent elements ofthe television ex300 are connected to each other through a synchronousbus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of Embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of Embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 15 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 16 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 14. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 17A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin Embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 17B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of Embodiments (i.e.,functions as the image coding apparatus of the present invention), andtransmits the coded video data to the multiplexing/demultiplexing unitex353. In contrast, during when the camera unit ex365 captures video,still images, and others, the audio signal processing unit ex354 codesaudio signals collected by the audio input unit ex356, and transmits thecoded audio data to the multiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of Embodiments (i.e., functions as the imagedecoding apparatus of the present invention), and then the display unitex358 displays, for instance, the video and still images included in thevideo file linked to the Web page via the LCD control unit ex359.Furthermore, the audio signal processing unit ex354 decodes the audiosignal, and the audio output unit ex357 provides the audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably have 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of Embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofEmbodiments can be obtained.

Furthermore, the present invention is not limited to Embodiments, andvarious modifications and revisions are possible without departing fromthe scope of the present invention.

Embodiment 4

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of Embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG4-AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconform cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of Embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG2-Transport Stream format.

FIG. 18 illustrates a structure of the multiplexed data. As illustratedin FIG. 18, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of Embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG4-AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary video to be mixed with the primary audio.

FIG. 19 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 20 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 20 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 20, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 21 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 21. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 22 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 23. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 23, the multiplexed data includes a system rate,a reproduction start time, and a reproduction end time. The system rateindicates the maximum transfer rate at which a system target decoder tobe described later transfers the multiplexed data to a PID filter. Theintervals of the ATSs included in the multiplexed data are set to nothigher than a system rate. The reproduction start time indicates a PTSin a video frame at the head of the multiplexed data. An interval of oneframe is added to a PTS in a video frame at the end of the multiplexeddata, and the PTS is set to the reproduction end time.

As shown in FIG. 24, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of Embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of Embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of Embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 25 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute information isobtained from the multiplexed data. Next, in Step exS101, it isdetermined whether or not the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of Embodiments. When it is determined that the stream type or thevideo stream attribute information indicates that the multiplexed datais generated by the moving picture coding method or the moving picturecoding apparatus in each of Embodiments, in Step exS102, decoding isperformed by the moving picture decoding method in each of Embodiments.Furthermore, when the stream type or the video stream attributeinformation indicates conformance to the conventional standards, such asMPEG-2, MPEG4-AVC, and VC-1, in Step exS103, decoding is performed by amoving picture decoding method in conformity with the conventionalstandards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of Embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard, an appropriatedecoding method or apparatus can be selected. Thus, it becomes possibleto decode information without any error. Furthermore, the moving picturecoding method or apparatus, or the moving picture decoding method orapparatus in the present embodiment can be used in the devices andsystems described above.

Embodiment 5

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of Embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 26 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of Embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recording mediaex215. When data sets are multiplexed, the data should be temporarilystored in the buffer ex508 so that the data sets are synchronized witheach other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present inventionis applied to biotechnology.

Embodiment 6

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of Embodiments isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG4-AVC, and VC-1 is decoded, the processingamount probably increases. Thus, the LSI ex500 needs to be set to adriving frequency higher than that of the CPU ex502 to be used whenvideo data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 27illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof Embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of Embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of Embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 26.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of Embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 26. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, the identification information described inEmbodiment 4 is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 4 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 29. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 28 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of Embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of Embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG4-AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofEmbodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG4-AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of Embodiments, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of Embodiments, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set higher. When the identification information indicates thatthe video data conforms to the conventional standard, such as MPEG-2,MPEG4-AVC, and VC-1, the voltage to be applied to the LSI ex500 or theapparatus including the LSI ex500 is probably set lower. As anotherexample, when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of Embodiments, the drivingof the CPU ex502 does not probably have to be suspended. When theidentification information indicates that the video data conforms to theconventional standard, such as MPEG-2, MPEG4-AVC, and VC-1, the drivingof the CPU ex502 is probably suspended at a given time because the CPUex502 has extra processing capacity. Even when the identificationinformation indicates that the video data is generated by the movingpicture coding method and the moving picture coding apparatus describedin each of Embodiments, in the case where the CPU ex502 has extraprocessing capacity, the driving of the CPU ex502 is probably suspendedat a given time. In such a case, the suspending time is probably setshorter than that in the case where when the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG4-AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 7

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a mobile phone. In order to enable decoding the pluralityof video data that conforms to the different standards, the signalprocessing unit ex507 of the LSI ex500 needs to conform to the differentstandards. However, the problems of increase in the scale of the circuitof the LSI ex500 and increase in the cost arise with the individual useof the signal processing units ex507 that conform to the respectivestandards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of Embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG4-AVC, and VC-1 are partly shared. Ex900 in FIG. 30A showsan example of the configuration. For example, the moving picturedecoding method described in each of Embodiments and the moving picturedecoding method that conforms to MPEG4-AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. The details ofprocessing to be shared probably include use of a decoding processingunit ex902 that conforms to MPEG4-AVC. In contrast, a dedicated decodingprocessing unit ex901 is probably used for other processing unique tothe present invention. Since the present invention is characterized byintra prediction processing in particular, for example, the dedicateddecoding processing unit ex901 is used for intra prediction processing.Otherwise, the decoding processing unit is probably shared for one ofthe entropy coding, inverse quantization, deblocking filtering, andmotion compensation, or all of the processing. The decoding processingunit for implementing the moving picture decoding method described ineach of Embodiments may be shared for the processing to be shared, and adedicated decoding processing unit may be used for processing unique tothat of MPEG4-AVC.

Furthermore, ex1000 in FIG. 30B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to the present invention, a dedicated decoding processing unitex1002 that supports the processing unique to another conventionalstandard, and a decoding processing unit ex1003 that supports processingto be shared between the moving picture decoding method in the presentinvention and the conventional moving picture decoding method. Here, thededicated decoding processing units ex1001 and ex1002 are notnecessarily specialized for the processing of the present invention andthe processing of the conventional standard, respectively, and may bethe ones capable of implementing general processing. Furthermore, theconfiguration of the present embodiment can be implemented by the LSIex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding method inthe present invention and the moving picture decoding method inconformity with the conventional standard.

INDUSTRIAL APPLICABILITY

The moving picture coding method and the moving picture decoding methodaccording to the present disclosure are capable of being applied to anymultimedia data and improving a compression rate. For example, they aresuitable as the moving picture coding method and the moving picturedecoding method for accumulation, transmission, communications, and thelike using mobile telephones, DVD apparatuses, personal computers, andthe like.

The invention claimed is:
 1. A moving picture decoding method fordecoding a current block, comprising: determining a first candidate anda second candidate, the first candidate having a first motion vectorthat has been used to decode a first block, and the second candidatehaving a second motion vector that has been used to decode a secondblock that is different from the first block; generating a new candidatehaving a third motion vector and a fourth motion vector, the thirdmotion vector being identical to the first motion vector, and the fourthmotion vector being identical to the second motion vector; and decodingthe current block by using a candidate from among a plurality ofcandidates including the first candidate, the second candidate, and thenew candidate.
 2. The moving picture decoding method according to claim1, wherein, when the candidate that is used to decode the current blockis the new candidate, the new candidate is used for bi-directionalpredict.
 3. The moving picture decoding method according to claim 1,wherein, when the candidate that is used to decode the current block isthe new candidate, the third motion vector of the new candidate and theforth motion vector of the new candidate are used for bi-directionalprediction.
 4. The moving picture decoding method according to claim 1,wherein a first reference picture list includes a first referencepicture index value to identify a first reference picture correspondingto the first motion vector, wherein a second reference picture listincludes a second reference picture index value to identify a secondreference picture corresponding to the second motion vector, andwherein, when the candidate that is used to decode the current block isthe new candidate, the current block is decoded by using the thirdmotion vector, the fourth motion vector, the first reference pictureindex value, and the second reference picture index value.
 5. A movingpicture decoding apparatus that decodes a current block, comprising: adetermination unit configured to determine a first candidate and asecond candidate, the first candidate having a first motion vector thathas been used to decode a first block, and the second candidate having asecond motion vector that has been used to decode a second block that isdifferent from the first block; a generation unit configured to generatea new candidate having a third motion vector and a fourth motion vector,the third motion vector being identical to the first vector, and thefourth motion vector being identical to the second motion vector; and adecoding unit configured to decode the current block by using acandidate from among a plurality of candidates including the firstcandidate, the second candidate, and the new candidate.